J
OURNAL OFD
EGRADED ANDM
ININGL
ANDSM
ANAGEMENTISSN: 2339-076X (p); 2502-2458 (e), Volume 5, Number 2 (January 2018): 1027-1034 DOI:10.15243/jdmlm.2018.052.1027
www.jdmlm.ub.ac.id 1027
Research Article
Mercury contamination in soil, tailing and plants on agricultural fields near closed gold mine in Buru Island, Maluku
Reginawanti Hindersah
1*, Robi Risamasu
2,A. Marthin Kalay
2, Triyani Dewi
3, Imran Makatita
41Universitas Padjadjaran Jalan Raya Bandung-Sumedang Km 21 Jatinangor 45363, Indonesia
2Universitas Pattimura Jalan Ir. Putuhena Kampus Poka Ambon 97233, Indonesia
3Agricultural Environment Research Centre, Jalan Raya Jakenan-Jaken KM 5, Jakenan, Pati 59182, Indonesia
4Agricultural Department of Buru District, Jalan Bunga Menur, Namlea 97371, Indonesia
* corresponding author : [email protected] Received 03 October 2017, Accepted 30 November 2017
Abstract:Agricultural productivity in Buru Island, Maluku is threatened by tailings which are generated from formerly gold mine in Botak Mountain in Wamsait Village. Gold that extracted by using mercury was carried out in mining area as well agricultural field. High content of mercury in tailings and agricultural field pose a serious problem of food production and quality; and further endangers human health. The purpose of this research was to determine the contaminant level of mercury in tailing, soil and its accumulation in edible part of some food crops. Soil, tailing and plant samples for Hg testing were taken by purposive method based on mining activities in Waelata, Waeapo and Namlea sub district. Six soil samples had been analyzed for their chemical properties. Total mercury levels in tailings and plants were measured by Atomic Adsorption Spectrophotometer. This study showed that agricultural field where tailings were deposited contained Hg above the threshold but agricultural area which is far from hot spot did not. Most edible parts of food crops accumulated mercury more than Indonesian threshold for mercury content in food. This evidence explained that tailings deposited on the surface of agricultural field had an impact on soil quality and crop quality. Tailing accumulated on soil will decreased soil quality since naturally soil fertility in agricultural field in Buru is low.
Keywords:gold mine, mercury, paddy field, soil quality.
To cite this article: Hindersah, R., Risamasu, R., Kalay, A.M., Dewi, T. and Makatita, I. 2018. Mercury contamination in soil, tailing and plants on agricultural fields near closed gold mine in Buru Island, Maluku. J.
Degrade. Min. Land Manage. 5(2): 1027-1034, DOI: 10.15243/jdmlm.2018.052.1027.
Introduction
Buru Regency in Maluku Province which cover an area of 5,577.48 km² is the center of food crop production especially rice in Eastern part of Indonesia. During 2011-2015, massive illegal gold mining occurred in Botak Mountain around Wamsait Village where Wamsait River and Anhoni River flow. The gold deposit at the site was the primary ore-type vein ore, which was mined by underground technique of gophering method.
The remaining tailings must be managed properly to reduce the amount of moisture and
avoid heavy metal discharge to stream and atmosphere before they are placed back on the underground or used for another purpose.
Unfortunately local miner communities had neither post mining management plan nor tailings management facility. In Botak Mountain, tailing from the upper zone of mountain flowed into the Anhoni River to reach the lower zone of area;
significant amount of tailing in lower zone was stored on nearby area and agricultural filed without any treatment. Tailing accumulated on the surface of sago plantation; former important staple food in Maluku. Mining material was also sold to local farmers or bigger miner and was
extracted in agricultural area.
agricultural area in Waelata and Waeapo sub districts are covered with tailings.
Efforts to increase the productivit crops now are threaten by gold Illegal miner has extracted gold amalgamation method by using mer one of the non-essential elements that has biological and physiological function cells (Gadd, 1992). Naturally, Hg
abundance in the Earth’s crust, The most important Hg mineral is cinnabar (HgS) appeared on earth firstly more than three years ago (Hazen et al., 2012). N
in soil is primarily determined by the composition of the parent material and the soil genesis ( 2005). Average Hg in world soils is
mg/kg - 5 mg/kg. However, our preliminary study at 2015 showed that Hg content of
Anhoni river basin was only 0.64 mg in tailings pile was 10.77 mg/kg.
by tailings contains Hg of 0.24 mg/
mg/kg. Mercury-containing tailing the open environment will be washed volatilized (Moreno et al., 2004)
transformations namely metallic and biological reduction (Morel et al., 1998) will take place. This poses ecological, food quality and health
of toxic contamination.
Tailings of gold mines have poor physical and chemical properties. They are
dominated by sand materials to
with low organic matter and low cation exchange capacity (Taberima et al., 2010)
Figure 1. Waelata, Waeapo and Namlea sub
Soil, tailing and plant sampling
Soil, tailing and plant samples for Hg testing were taken by purposive method based on mining activities in Waelata, Waeapo and Namlea sub districts. Soil samples for chemical analysis were taken by purposive method from six area. In certain area, ta and Waeapo sub- covered with tailings.
Efforts to increase the productivity of food by gold-mine tailings.
has extracted gold with using mercury (Hg);
essential elements that has no logical and physiological function in normal Naturally, Hg is low abundance in the Earth’s crust, The most t Hg mineral is cinnabar (HgS), which on earth firstly more than three billion 2012). Natural Hg content soil is primarily determined by the composition he soil genesis (Bradl, in world soils is only 0.15 our preliminary study Hg content of tailings in the only 0.64 mg/kg but those /kg. The soil covered 0.24 mg/kg to 20.36 tailing which is left in the open environment will be washed; eroded and 2004), and biochemical llic and biological reduction (Morel et al., 1998) will take place. This and health problem Tailings of gold mines have poor physical . They are usually to silty materials and low cation exchange capacity (Taberima et al., 2010). The acidity of
tailing is extreme; very acid or too
These properties are less supportive of plant growth and high Hg levels are potentiall accumulating in edible part of food crop.
After mining activity is officially
Government of Maluku, assessment concerning Hg contaminant levels in the upper watersheds Wamsiat and Anhoni river as well as
agricultural areas has never possibility of Hg contamination
food crops grown in contaminated area been ascertained. This research was conduc study the fertility of native soil,
tailing and soil; and Hg accumulation in part of food crops grown in tailing tailing-contaminated soil in agricultural field Buru District.
Materials and Methods The research was conducted
Maluku Province. Soil and plant analyzes were conducted at the Agricultural Environment Research Institute in Pati
Department of Agriculture. Samples were taken from several villages in three sub
1) close to Botak Mountain:
1. Wamsait and Parbulu Village in Waelata sub district.
2. Waikerta, Wanareja, Waitele Village, Savana Jaya Village in Waeapo
3. Siahoni Village in Namlea
1. Waelata, Waeapo and Namlea sub-districts in Buru District map
amples for Hg testing were taken by purposive method based on mining activities in Waelata, Waeapo and Namlea sub for chemical analysis were taken by purposive method from six
uncontaminated paddy field with wet land rice system in Waelata and Waeapo sub district.
soil samples had been analyzed for their properties (Table 1). Three
taken from each sampling point
of 30 cm using auger kit. The three soil samples ware mixed and placed in a labeled sample bag.
very acid or too alkaline.
are less supportive of plant growth and high Hg levels are potentially
edible part of food crop.
is officially closed by ssessment concerning Hg contaminant levels in the upper watersheds of Wamsiat and Anhoni river as well as surrounding ever been done. The contamination in edible part of grown in contaminated area has not been ascertained. This research was conducted to fertility of native soil, level of Hg in accumulation in the edible part of food crops grown in tailing pile and in agricultural field of
was conducted in Buru District of oil and plant analyzes were Agricultural Environmental which belong to Samples were taken sub-districts (Figure and Parbulu Village in Waelata sub- , Waitele Village, and vana Jaya Village in Waeapo sub-district.
Namlea sub-district.
in Buru District map
uncontaminated paddy field with wet land rice Waelata and Waeapo sub district. Six been analyzed for their chemical soil samples were sampling point to depth of tillage . The three soil samples in a labeled sample bag.
Mercury contamination in soil, tailing and plants on agricultural fields near closed gold mine
Journal of Degraded and Mining Lands Management 1029
The soils were air dried for one week and passed through a 2-mm sieve prior to laboratory analyses to obtain soil fertility profile. The soil analyses were determined as follows: soil acidity, total C- organic, N-total, P and K total, available P, Cation exchange capacity, exchangeable cations, base saturation, and soil texture determination. The methods of soil testing for all soil parameters are presented in Table 1. Another soil and tailing samples were taken by using similar sampling method for mercury testing. Some soil samples were taken from uncontaminated site as a
reference to compare the results. Tailing sample was collected from tailing pile near agricultural field. Edible part of food crops grown naturally on contaminated and uncontaminated soils was also collected. Soil and tailing were air dried and plant samples were dried at 70oC for two consecutive days before mercury testing. Total mercury levels in tailings and plants were
measured by Atomic Adsorption
Spectrophotometer after sample extraction with 1 mL of perchloric acid p.a. and 5 mL of nitric acid p.a. (Sulaeman et al., 2005).
Table 1. Soil testing methods of certain chemical soil parameters
Soil Parameter Testing Method Unit
Soil acidity (pHH2O) Potentiometric
Soil acidity (pHKCl) Potentiometric
Organic Carbon Walkley & Black %
Total Nitrogen Kjeldahl %
C/N - -
Potential K HCl 25% mg/100g
Potential P2O5 HCl 25% mg/100g
Available P2O5 Olsen mg/kg P
Cation Exchange Capacity Extract NH4OAc pH 7 cmol/kg
Base saturation %
Exchangeable cation: Na2, Ca2, K+, Mg2+ Extract NH4OAc pH 7 cmol/kg
Results and Discussion Soil characteristics and fertility
Waeapo plain where recent paddy fields were constructed was formed about 50 years ago; the natural vegetation grown on this area was sago;
traditional staple food. Actual rice yields in Waeapo plain was generally; less than those of paddy yield potential in most irrigated paddy production center in Indonesia, up to 8 t/ha. In Waeapo plain, rice productivity in the planting season of April-September 2014 was about 4.5 t/ha. Only a small amount of paddy field produce rice more around 6 t/ha. Chemical profile of six soil collected from six village was depicted in Table 1. All samples of paddy soil were slightly acid to neutral in acidity. Wetland rice systems have a positive effect on chemical fertility by bringing pH in the neutral range (Sahrawat, 2005).
In neutral soil, plant nutrient is more available for roots uptake. A neutral soil acidity inhibit heavy metal movements in the soil so that potential poisoning from heavy metals can be suppressed (Bradl, 2005); heavy metal washing does not occur on neutral soil acidity.
Six sampling spots contained low organic Carbon and total Nitrogen; either their potential P or K of all soil sample was low (Table 2). Soil
pudding creates organic matter accumulation due to reduced oxygen supply. In turn limited organic matter decomposition promotes formation of impermeable layer which reduces percolation losses. However, surface water and the first few millimeters of top soil remain relatively oxidized (Sahrawat, 2005). Irrigation system in Buru District is ceased in dry season so that farmers have no opportunity to grow rice twice consecutively. Since impermeable soil layer in Buru’s paddy field has not been formed, in dry season submerged paddy soil dried up which in turn aerobic condition induce biological activity to decompose organic matter. Low soil organic matter explained the fact that organic matter application is very limited (Yadav et al., 2000) since the farmer in Buru mixed organic matter only recently.
All soils were low in cation exchange capacity (CEC) whereas their base saturation (BS) varied from very low to average (Table 2). Soil fertility status is determined by CEC, BS, potential P, potential K and organic C. Based on the data in Table 2, the soil fertility status of all soil samples were low (Table 3). Naturally, previous native plant in recent paddy field was sago (Metroxylon sagu Rottb; Arecacea) which
was grown in wet land.
Table 2. Soil chemistry profile in six village in Buru District
Soil sampling location pH Organic Total N Available Potential Potential CEC Cationex BS
(village) Carbon P K P- K Na Ca Mg %
% mg/kg cmol(+)/ kg
Parbulu 6.86 0.32 0.09 4.7 8.0 9.0 6.95 0.26 1.17 1.71 0.27 48.9
Wamsait 6.25 0.64 0.13 9.4 7.4 8.3 10.64 0.26 0.40 2.23 0.52 32.0
Waekerta 7.25 0.25 0.09 7.1 3.7 3.9 6.16 0.14 1.08 0.95 0.28 39.7
Savana Jaya 6.65 0.25 0.07 10.6 2.4 7.0 8.47 0.10 0.40 3.16 0.48 48.7
Waelata 6.31 0.36 0.06 8.2 3.9 8.5 9.35 0.12 0.39 0.73 0.34 16.8
Wanareja 6.31 0.52 0.10 8.5 4.6 4.9 10.16 0.09 0.43 1.06 0.56 21.1
CEC = cation exchange capacity; BS = base saturation
Mercury contamination in soil, tailing and plants on agricultural fields near closed gold mine
Journal of Degraded and Mining Lands Management 1031
Sago grows in swampy areas, marginal soils or high water content soil (Louhenapessy, 2008). In North Maluku, total N, P and K contents of sago soil are low; and land suitability for irrigated paddy field was only marginally suitable (S) due to N, P and K availability (Ibrahim and Gunawan,
2015). Long-term effect of low organic matter in paddy soil will relate to low potentially nitrogen mineralization and soil neutrality which in turn resulting in low nutrient availability (Sahrawat, 1983).
Table 3. Fertility status of soil in six villages at Buru District based on five soil chemical properties Village CEC BS Potential P Potential K Organic
Carbon
Soil Fertility status
Parbulu Low Average Low Low Low Low
Wamsait Low Low Low Very low Low Low
Waekerta Low Average Very Low Very low Low Low
Savana Jaya Low Average Low Very low Low Low
Waelata Low Very low Low Very low Low Low
Wanareja Low Low Low Very low Low Low
Mercury levels in tailing and soil
Soil testing on total mercury level in soil verified that its level was differed depending on the vicinity of sampling point to tailing deposit (Table 3). Quantification of soil Hg used a strong acid mixed extraction method before Hg content was measured by using an atomic adsorption spectrometry device. This method measures the overall form of Hg; both unstable Hg-inorganic and organic Hg. Table 3 shows that Hg content in tailings and suspected Hg- contaminated area were higher than that of agricultural field that is far from the mine site.
Generally the world's Hg levels in the world are 0.3-5 mg/kg (Steinnes, 1995); uncontaminated agricultural land contains Hg between 1-5 mg/kg, still in the normal range. Naturally agricultural fields (rice fields and vegetable areas) in the working area contains high enough Hg even two area contain Hg slightly that exceeded the upper limit of 5 mg/kg.
According to Government Regulation no.
82 year 2002, maximum permitted level of Hg in environment is < 0.001 mg/kg in water, and
<0.15 mg/kg in soil. According to Steinnes (1995), Hg levels in soil depend on the process of soil genesis and mineral composition of parent material. However, most top soils and tailing pile contained increased amounts of Hg, especially near mining area (Table 3). This finding agreed with our previous study.
Mercury in two soil samples collected from rhizosphere of pioneer plant grown in tailing in Waeapo village was 9.06 and 20.36 mg/kg respectively.
In general, the accumulation of Hg in the soil relates with deposition from anthropogenic activity through biosphere or atmosphere.
Tailing pile in Namlea (Table 3) contained up to 166.10 mg/kg of Hg due to double gold extraction by using more Hg. Mercury is also a volatile metal that can be transported over a distance of 20-100 km. Therefore, naturally, soil enrichment by Hg is rarely observable on a wide scale. In this study, it is clear that Hg content in the suspected uncontaminated soil is far below the Hg level on agricultural field affected by gold tailings. Mercury and their compounds present in the soil fractions vary in the degree of mobility (Kabata Pendiaz and Mukherjee, 2007). Similar to other soil heavy metals, mercury bioavailability is regulated by physical, chemical and biological processes and interactions between them (Steinnes, 1995).
Elevated level of mercury in gold-mine tailing is supposed to threaten rice production but the fact that soil reaction is neutral; and the availability of mercury in soil to plants might be quite low.
Mercury levels in edible parts of food crops Maximum permitted mercury in edible parts of plant was 50 μg/kg according to Bradl (2005).
Mercury in edible parts of vegetables grown on tailings-free field was lower than 50 μg/kg whereas those grown on tailings as well as on tailings-affected land contained more than 50 μg/kg of Hg (Table 4). Mercury-contaminated rice was an intense issue in Buru but it was not supported by real data. This study showed that grain from rice field irrigated by water from gold mine area only contained 31.16 μg/kg of Hg; slightly higher than those received uncontaminated water; 25.96 μg/kg. Low Hg levels in rice grain is an indication that rice from Buru might not contaminated by Hg.
Table 3. Mercury levels in soil, tailings and agricultural field in Buru District
No Sub district Village Agricultural Field Hg Level
(mg/kg) Contaminated Agricultural Field
1 Waelata Wamsait (Path A) Grassland soil 30.66
2 Wamsait (Path B) Mixed garden soil 13.70
3 Wamsait (Path C) Mixed garden 15.08
4 Wamsait (Path C) Former paddy field soil 22.51
5 Parbulu Tailing on Watercrest area 96.47
6 Parbulu Tailing on cocoa plantation 22.19
7 Parbulu Submerged tailing 26.97
8 Waeapo Wanareja Paddy field soil 35.68
9 Wanareja Soybean field soil 9.92
10 Wanareja Paddy field (1) soil 19.74
11 Wanareja Paddy field (2) soil 26.98
12 Waikerta Tailing on fruit orchard (1) 26.06
13 Waikerta Tailing on Fruit orchard (2) 11.37
14 Waikerta Tailing on Cocoa plantation 19.50
15 Waikerta Tailing on vegetable area 11.01
16 Namlea Siahoni Tailing in mining installations 166.10
Uncontaminated Agricultural Field
1 Waelata Parbulu Paddy field soil, Parbulu 5.84
2 Wamsait Grass field (former paddy field) soil 4.22
3 Waeapo Waikerta Paddy field soil 3.78
4 Savana Jaya Vegetable área soil 1.64
5 Waetele Paddy field soil 2.81
6 Wanareja Paddy field soil 5.36
Agricultural lands covered with Hg-contaminated tailing pose two main problem. First, tailings pile on agricultural area will decrease soil quality.
Tailing from Anhoni river inhibited nodules formation and groundnut growth in pot culture (Pramya, 2015) although liming and organic matter application was carried. Mine tailings present only a suitable substrate for establishment native plant species such as
Lygeum spartum, Zygophyllum
fabagoandPiptatherum miliaceum (Conesa et al., 2007). A short-term experiment indicated that
native plant species Prosopis
velutinaandAmaranthus watsonii grow in metal mine tailings are potential for heavy metal phytostabilization (Santos et al., 2017). Native plants have colonized some Buru tailings area, although the distribution is localized and uneven;
their slow growth may not sufficient to cover tailing deposit area in short time. Native plants
grow on Buru tailing mostly grass ofCyperussp.
Eulesin sp., and Cynodon dactylon. Revegetation of tailing on agricultural soil is the first step to improve soil quality in order to be used as food crop’s plant substrate. Using native plant might be a more effective and less cost rehabilitation although take a relatively long time.
The second problem is crushing materials in the process of gold extraction causes heavy metals is released to the environment, not just Hg.
Tailing pile in Buru contain Zn and Cd, similar to tailings of gold mines in Thailand which contain Co, Cu, Cd, Cr, Pb, Ni and Zn (Changul et al., 2010). In 2015, the Energy and Mineral Resources Department of Maluku Province has collected tailings from rivers and river basin and that deposited in watersheds. The reduction of toxicity and heavy metal content should be done before tailing release to agricultural field.
Mercury contamination in soil, tailing and plants on agricultural fields near closed gold mine
Journal of Degraded and Mining Lands Management 1033
Table 4. Levels of mercury in edible part of plant grown in the tailings pile, tailings-impacted area and free-tailing agricultural field.
Sub District
Village Agricultural field Plant/ Commodities Hg (µg/kg)
Waelata Wamsait Tailing deposit Grass 76.95
Agricultural area, irrigated by waste water from mining installation
Cassava tuber 89.05
Cassava leaves 80.78
Tailing affected agricultural area Tomato 78.94
Eggplant 66.54
Watercress 78.64
Cai sim 84.92
Cauliflower 90.12
Chili 89.05
Parbulu Paddy field, lower zone of mining installations
Paddy grain irrigated with contaminated water
31.16 Paddy grain irrigated with
uncontaminated water
25.96
Cucumber 43.42
Home garden has been irrigated with supposed Hg-contaminated water
Chili 6807
Eggplant 73.43
Local bay leaves 56.28
Local squash 28.56
Near mining installations Watercress 70.52
Waeapo Savana Jaya
Uncontaminated vegetable area Spring onion 31.62
Cucumber 38.21
Long bean 41.73
Cauliflower 46.78
Tomato 46.94
Waekerta Uncontaminated vegetable area Tomato 49.08
chayote 48.77
Conclusion
Gold mining activities in the Botak Mountain of Buru Maluku District produced Hg-contaminated tailings deposited at river and water shed area near mine site, and agricultural land. The mercury content in tailings and tailing-contaminated soil were above the average mercury in the world's soils but their levels in some agricultural area far from mining installation were low and within the normal range. Edible parts of most food crops grown on contaminated soil contained Hg more than permitted level of 50μg/ kg but Hg level of those in uncontaminated soil were below the threshold. The results of this study explained that mine tailing was contaminated by Hg, but agricultural land far from mining installation still contains Hg within the normal range. To ensure
the safety of Agricultural area in the Weapo valley, it is necessary to delineate Hg within the agricultural area located in the vicinity of mining installation in Botak Mountain.
Acknowledgement
We are grateful to Buru District Agriculture Office for financial support. We thank all officials who supported this study.
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